This invention generally relates to compressors, and more specifically to compressors employing suction mufflers to attenuate sound waves generated within the compressors.
Compressors are commonly employed in refrigeration and air conditioning equipment to compress a refrigerant vapor. Commonly, a compressor includes a cylinder block, a plurality of cylinder heads, a rotatable crankshaft, and a plurality of pistons. The compressor crankshaft is rotatably supported by the cylinder block, and the cylinder block defines a plurality of cylinder chambers. The compressor pistons are reciprocally disposed within these cylinder chambers and are also connected to the compressor crankshaft via conventional wrist pins and connecting arms. The cylinder heads cover the cylinder chambers and define suction plenums for conducting vapor thereinto and discharge plenums for receiving compressed vapor therefrom. Suction and discharge valves are positioned between the cylinder chambers and the suction and discharge plenums to control vapor flow therebetween.
Often, a compressors of the general type outlined above is utilized as part of a motor-compressor unit that, in addition to the compressor, includes a motor and a shell enclosing both the compressor and the motor. In operation, the shell of the motor-compressor unit is filled with low pressure suction vapor, the motor is employed to rotate the compressor crankshaft, and rotation of the crankshaft reciprocates the compressor pistons within the cylinder chambers. As these pistons reciprocate, vapor is drawn through the suction plenums defined by the cylinder heads and into the cylinder chambers, compressed therein, and then directed into the discharge plenums of the cylinder heads. Therefrom, the compressed vapor is conducted from the compressor and from the shell of the motor-compressor unit via a vapor discharge line. As is well understood in the art, the suction and discharge valves cyclically open and close to insure that vapor flows in the proper sequence from the suction plenum into the cylinder chambers and from the cylinder chambers into the discharge plenums.
This cyclic opening and closing of the suction valves generates pressure pulses in the vapor flow path leading to the suction valves. These pressure pulses may be transmitted along this vapor flow path to the shell of the motor-compressor unit, and the shell may transmit these pressure pulses to the ambient, producing undesirable noise. In order to dissipate these pressure pulses and to prevent the concomitant noise, compressors of the general type discussed above are often provided with mufflers, commonly referred to as suction mufflers. The suction mufflers are connected to the cylinder heads of the compressor, define fluid flow paths to conduct vapor into the suction plenums of the cylinder heads, and, in operation, diffuse the pressure pulses developed by the suction valves, substantially reducing any noise generated thereby.
Heretofore, these suction mufflers have been formed from a metal and usually are either integral with or bolted to the cylinder heads or the cylinder block of the compressor. While these mufflers perform very satisfactorily, they have a number of disadvantages. Principally, the raw material and the process of forming the mufflers are both costly. Moreover, metal suction mufflers, being good conductors of heat, conduct some heat from the discharge plenums of the cylinder heads to the vapor flowing through the mufflers, heating that vapor. This may have a slight adverse affect on the performance of the compressor.